1. Field of the Invention
The invention relates to a device for hydrostatic pressure determination using an ultrasonic transmitter and an ultrasonic receiver, and to a method for determining the hydrostatic pressure using the device.
2. Prior Art
Determining the pressure of liquids in high-pressure containers is necessary above all in measuring the diesel fuel pressure in common rails or in gasoline injection technology, in which liquid pressures of up to 2000 bar occur. In other areas of industry as well, pressures of liquid in high-pressure containers are measured.
Various pressure measuring techniques for this are known.
As one example, it is possible to integrate a diaphragm or other deformable body, as a pressure sensor, with the wall of the high-pressure container, and the deflection of this sensor is then measured on the piezoresistive principle, for instance with a rail pressure sensor, or capacitively.
A pressure sensor may also be mounted entirely inside the high-pressure chamber and thus directly in the medium to be measured, as is the case for example in “vibrating cylinder” measurement or in the use of piezoresistive materials, such as highly porous RuO2, which alters its electrical transporting properties under the influence of hydrostatic pressures.
The disadvantage of the known pressure-measuring techniques is the necessity for seals. In the case where the sensor is integrated with the wall of the high-pressure container, the entire surroundings of the sensor must be sealed off from the exterior; otherwise, at least high-pressure contact leadthroughs are required.
Because of the problems of tightness in high-pressure containers, it is appropriate for there to be as few interfaces with the exterior as possible. If the contacts are the only elements that must be passed through the wall, then the problem is indeed reduced but not yet eliminated. Moreover, measuring methods as vibrating cylinder measurement are complicated and expensive and thus are poorly suited to use in a mass-produced article, such as a conventional Diesel common rail.